diff options
| author | Kent Overstreet <kent.overstreet@linux.dev> | 2023-12-12 20:08:29 -0500 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2024-01-01 11:47:44 -0500 |
| commit | fea153a84557c982542527143950dbef434731c2 (patch) | |
| tree | 7fc53a84018c9d7ed237cfcd9e342da3cbd1d25f /fs/bcachefs/btree_iter.c | |
| parent | 6474b706108bac9e531a71ddeb8150f8fa17163c (diff) | |
bcachefs: rcu protect trans->paths
Upcoming patches are going to be changing trans->paths to a
reallocatable buffer. We need to guard against use after free when it's
used by other threads; this introduces RCU protection to those paths and
changes them to check for trans->paths == NULL
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/btree_iter.c')
| -rw-r--r-- | fs/bcachefs/btree_iter.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c index ced13bbc52f7..818676b97436 100644 --- a/fs/bcachefs/btree_iter.c +++ b/fs/bcachefs/btree_iter.c @@ -2920,6 +2920,8 @@ struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx) trans->sorted = trans->_sorted; trans->paths = trans->_paths; + *trans_paths_nr(trans->paths) = BTREE_ITER_MAX; + trans->paths_allocated[0] = 1; s = btree_trans_stats(trans); @@ -3074,12 +3076,14 @@ bch2_btree_bkey_cached_common_to_text(struct printbuf *out, void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans) { - struct btree_path *path; struct btree_bkey_cached_common *b; static char lock_types[] = { 'r', 'i', 'w' }; struct task_struct *task = READ_ONCE(trans->locking_wait.task); unsigned l, idx; + /* before rcu_read_lock(): */ + bch2_printbuf_make_room(out, 4096); + if (!out->nr_tabstops) { printbuf_tabstop_push(out, 16); printbuf_tabstop_push(out, 32); @@ -3087,7 +3091,18 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans) prt_printf(out, "%i %s\n", task ? task->pid : 0, trans->fn); - trans_for_each_path(trans, path, idx) { + /* trans->paths is rcu protected vs. freeing */ + rcu_read_lock(); + out->atomic++; + + struct btree_path *paths = rcu_dereference(trans->paths); + if (!paths) + goto out; + + unsigned long *paths_allocated = trans_paths_allocated(paths); + + trans_for_each_path_idx_from(paths_allocated, *trans_paths_nr(paths), idx, 1) { + struct btree_path *path = paths + idx; if (!path->nodes_locked) continue; @@ -3120,6 +3135,9 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans) bch2_btree_bkey_cached_common_to_text(out, b); prt_newline(out); } +out: + --out->atomic; + rcu_read_unlock(); } void bch2_fs_btree_iter_exit(struct bch_fs *c) |